Accept multierr on racy teardown discovery tests

tests/test_discovery.py

@@ -206,7 +206,8 @@ def test_subactors_unregister_on_cancel(
     """Verify that cancelling a nursery results in all subactors
     deregistering themselves with the arbiter.
     """
-    with pytest.raises(KeyboardInterrupt):
+    # multi-error since there might be a channel breakage race?
+    with pytest.raises((KeyboardInterrupt, trio.MultiError)):
         trio.run(
             partial(
                 spawn_and_check_registry,
@@ -231,7 +232,7 @@ def test_subactors_unregister_on_cancel_remote_daemon(
     deregistering themselves with a **remote** (not in the local process
     tree) arbiter.
     """
-    with pytest.raises(KeyboardInterrupt):
+    with pytest.raises((KeyboardInterrupt, trio.MultiError)):
         trio.run(
             partial(
                 spawn_and_check_registry,